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#include <TestStdAlgorithmsCommon.hpp>
#include <std_algorithms/Kokkos_BeginEnd.hpp>
#include <std_algorithms/Kokkos_ModifyingSequenceOperations.hpp>
#include <utility>

namespace Test {
namespace stdalgos {
namespace ReplaceCopyIf {

namespace KE = Kokkos::Experimental;

template <class ViewType>
void fill_view(ViewType dest_view, const std::string& name) {
  using value_type      = typename ViewType::value_type;
  using exe_space       = typename ViewType::execution_space;
  const std::size_t ext = dest_view.extent(0);
  using aux_view_t      = Kokkos::View<value_type*, exe_space>;
  aux_view_t aux_view("aux_view", ext);
  auto v_h = create_mirror_view(Kokkos::HostSpace(), aux_view);

  if (name == "empty") {
    // no op
  }

  else if (name == "one-element-a") {
    v_h(0) = static_cast<value_type>(1);
  }

  else if (name == "one-element-b") {
    v_h(0) = static_cast<value_type>(2);
  }

  else if (name == "two-elements-a") {
    v_h(0) = static_cast<value_type>(1);
    v_h(1) = static_cast<value_type>(2);
  }

  else if (name == "two-elements-b") {
    v_h(0) = static_cast<value_type>(2);
    v_h(1) = static_cast<value_type>(-1);
  }

  else if (name == "small-a") {
    for (std::size_t i = 0; i < ext; ++i) {
      v_h(i) = value_type{-5} + static_cast<value_type>(i + 1);
    }
    v_h(0) = static_cast<value_type>(2);
    v_h(3) = static_cast<value_type>(2);
    v_h(5) = static_cast<value_type>(2);
  }

  else if (name == "small-b") {
    for (std::size_t i = 0; i < ext; ++i) {
      if (i < 4) {
        v_h(i) = static_cast<value_type>(-1);
      } else {
        v_h(i) = static_cast<value_type>(2);
      }
    }
  }

  else if (name == "medium" || name == "large") {
    for (std::size_t i = 0; i < ext; ++i) {
      if (i % 2 == 0) {
        v_h(i) = static_cast<value_type>(-1);
      } else {
        v_h(i) = static_cast<value_type>(2);
      }
    }
  }

  else {
    throw std::runtime_error("invalid choice");
  }

  Kokkos::deep_copy(aux_view, v_h);
  CopyFunctor<aux_view_t, ViewType> F1(aux_view, dest_view);
  Kokkos::parallel_for("copy", dest_view.extent(0), F1);
}

template <class ViewTypeFrom, class ViewTypeTest, class ValueType>
void verify_data(const std::string& name, ViewTypeFrom view_from,
                 ViewTypeTest view_test, ValueType new_value) {
  //! always careful because views might not be deep copyable
  auto view_test_dc = create_deep_copyable_compatible_clone(view_test);
  auto view_test_h =
      create_mirror_view_and_copy(Kokkos::HostSpace(), view_test_dc);

  auto view_from_dc = create_deep_copyable_compatible_clone(view_from);
  auto view_from_h =
      create_mirror_view_and_copy(Kokkos::HostSpace(), view_from_dc);

  // we check that view_from is unchanged from what it was after filling
  // while view_test should be changed

  if (name == "empty") {
    // no op
  }

  else if (name == "one-element-a") {
    EXPECT_TRUE(view_from_h(0) == ValueType{1});
    EXPECT_TRUE(view_test_h(0) == view_from_h(0));
  }

  else if (name == "one-element-b") {
    EXPECT_TRUE(view_from_h(0) == ValueType{2});
    EXPECT_TRUE(view_test_h(0) == new_value);
  }

  else if (name == "two-elements-a") {
    EXPECT_TRUE(view_from_h(0) == ValueType{1});
    EXPECT_TRUE(view_from_h(1) == ValueType{2});

    EXPECT_TRUE(view_test_h(0) == view_from_h(0));
    EXPECT_TRUE(view_test_h(1) == new_value);
  }

  else if (name == "two-elements-b") {
    EXPECT_TRUE(view_from_h(0) == ValueType{2});
    EXPECT_TRUE(view_from_h(1) == ValueType{-1});

    EXPECT_TRUE(view_test_h(0) == new_value);
    EXPECT_TRUE(view_test_h(1) == view_from_h(1));
  }

  else if (name == "small-a") {
    for (std::size_t i = 0; i < view_test_h.extent(0); ++i) {
      if (i == 0 || i == 3 || i == 5 || i == 6) {
        EXPECT_TRUE(view_from_h(i) == ValueType{2});
        EXPECT_TRUE(view_test_h(i) == new_value);
      } else {
        const auto gold = ValueType{-5} + static_cast<ValueType>(i + 1);
        EXPECT_TRUE(view_from_h(i) == gold);
        EXPECT_TRUE(view_test_h(i) == gold);
      }
    }
  }

  else if (name == "small-b") {
    for (std::size_t i = 0; i < view_test_h.extent(0); ++i) {
      if (i < 4) {
        EXPECT_TRUE(view_from_h(i) == ValueType{-1});
        EXPECT_TRUE(view_test_h(i) == view_from_h(i));
      } else {
        EXPECT_TRUE(view_from_h(i) == ValueType{2});
        EXPECT_TRUE(view_test_h(i) == new_value);
      }
    }
  }

  else if (name == "medium" || name == "large") {
    for (std::size_t i = 0; i < view_test_h.extent(0); ++i) {
      if (i % 2 == 0) {
        EXPECT_TRUE(view_from_h(i) == ValueType{-1});
        EXPECT_TRUE(view_test_h(i) == view_from_h(i));
      } else {
        EXPECT_TRUE(view_from_h(i) == ValueType{2});
        EXPECT_TRUE(view_test_h(i) == new_value);
      }
    }
  }

  else {
    throw std::runtime_error("invalid choice");
  }
}

std::string value_type_to_string(int) { return "int"; }
std::string value_type_to_string(double) { return "double"; }

template <class ValueType>
struct EqualsTwoFunctor {
  KOKKOS_INLINE_FUNCTION
  bool operator()(const ValueType val) const { return (val == ValueType(2)); }
};

template <class Tag, class ValueType, class InfoType>
void run_single_scenario(const InfoType& scenario_info) {
  const auto name            = std::get<0>(scenario_info);
  const std::size_t view_ext = std::get<1>(scenario_info);
  // std::cout << "replace_copy_if: " << name << ", " <<
  // view_tag_to_string(Tag{})
  //           << ", " << value_type_to_string(ValueType()) << std::endl;

  ValueType new_value{43};
  auto view_from =
      create_view<ValueType>(Tag{}, view_ext, "replace_copy_if_from");
  using pred_type = EqualsTwoFunctor<ValueType>;

  {
    fill_view(view_from, name);
    auto view_dest =
        create_view<ValueType>(Tag{}, view_ext, "replace_copy_if_dest");
    auto rit = KE::replace_copy_if(exespace(), KE::cbegin(view_from),
                                   KE::cend(view_from), KE::begin(view_dest),
                                   pred_type(), new_value);
    verify_data(name, view_from, view_dest, new_value);
    EXPECT_TRUE(rit == (KE::begin(view_dest) + view_ext));
  }

  {
    fill_view(view_from, name);
    auto view_dest =
        create_view<ValueType>(Tag{}, view_ext, "replace_copy_if_dest");
    auto rit = KE::replace_copy_if("label", exespace(), KE::cbegin(view_from),
                                   KE::cend(view_from), KE::begin(view_dest),
                                   pred_type(), new_value);
    verify_data(name, view_from, view_dest, new_value);
    EXPECT_TRUE(rit == (KE::begin(view_dest) + view_ext));
  }

  {
    fill_view(view_from, name);
    auto view_dest =
        create_view<ValueType>(Tag{}, view_ext, "replace_copy_if_dest");
    auto rit = KE::replace_copy_if(exespace(), view_from, view_dest,
                                   pred_type(), new_value);
    verify_data(name, view_from, view_dest, new_value);
    EXPECT_TRUE(rit == (KE::begin(view_dest) + view_ext));
  }

  {
    fill_view(view_from, name);
    auto view_dest =
        create_view<ValueType>(Tag{}, view_ext, "replace_copy_if_dest");
    auto rit = KE::replace_copy_if("label", exespace(), view_from, view_dest,
                                   pred_type(), new_value);
    verify_data(name, view_from, view_dest, new_value);
    EXPECT_TRUE(rit == (KE::begin(view_dest) + view_ext));
  }

  Kokkos::fence();
}

template <class Tag, class ValueType>
void run_all_scenarios() {
  const std::map<std::string, std::size_t> scenarios = {
      {"empty", 0},          {"one-element-a", 1},  {"one-element-b", 1},
      {"two-elements-a", 2}, {"two-elements-b", 2}, {"small-a", 9},
      {"small-b", 13},       {"medium", 1103},      {"large", 101513}};

  for (const auto& it : scenarios) {
    run_single_scenario<Tag, ValueType>(it);
  }
}

TEST(std_algorithms_replace_ops_test, replace_copy_if) {
  run_all_scenarios<DynamicTag, int>();
  run_all_scenarios<StridedThreeTag, int>();
  run_all_scenarios<DynamicTag, double>();
  run_all_scenarios<StridedThreeTag, double>();
}

}  // namespace ReplaceCopyIf
}  // namespace stdalgos
}  // namespace Test
